The present invention relates to an apparatus for watering surfaces, in particular plants, with at least one moveable beam on which are arranged several valves for dispensing water, the degree of opening of which can be adjusted continuously.
Such apparatuses are used in particular for watering plants, mainly on large-area flat surfaces, and the moveable beam can rotate around a central point of rotation or move in a linear manner. There are also hybrid forms in which the beam firstly moves in a linear manner, then changes to a rotary motion, and lastly moves in a linear manner again. With all these apparatuses for watering plants, it is important to apply a correctly metered amount of water to the ground. It is already known in this context to use valves whose flow is continuously adjustable (variable proportional valve) in contrast to on-off valves that can just be opened.
The object of the invention is to improve an apparatus of the type described hereinabove to the extent that the amount of water dispensed by the individual valves can be determined in a precisely metered manner.
According to the invention, this is solved in that at least some of the valves are each provided with means for direct or indirect sensing of an actual flow value, and an electronic regulating means that regulates the degree of opening of the valve until the actual flow value corresponds to a reference flow value pre-determined by a central control means.
Thus it is not simply a case of transmitting an adjustment value for the valve member to the valves, as with decreasing pressure conditions in the water supply line for the different nozzles and the initial positioning of the valve member, this would lead to less exact flow control. Instead, the flow is regulated at the site of the valve, in that an actual flow value is detected and the valve member adjusts the degree of opening of the valve by means of an integrated electronic regulating means until the reference flow value pre-determined by the central control means is actually obtained. As with a known outlet nozzle size and with a known ambient pressure, the flow is a direct function of the pressure after the valve member or respectively in front of the outlet nozzle, there is an advantageous possibility that the flow regulation in the valve can take place by means of pressure regulation, wherein a unit converts the reference flow value, by means of further parameters such as the diameter of an outlet nozzle and/or the external air pressure, into a reference pressure value, and the regulating means adjusts the degree of opening of the valve until the actual pressure value detected by the pressure sensor corresponds to the reference pressure value calculated.
A sturdy valve that has no sealing problems is characterised in that it is provided with an elastic hose, wherein a valve member acting externally upon the hose compresses it and the flow is adjustable by means of the variable pinch point thus formed in the interior of the hose.
Further advantages of the details of the invention will be explained in more detail with reference to the following description of the drawings.